1. Field of the Invention
The present invention relates to an image blur correction apparatus (image stabilization apparatus) that performs image blur correction (image stabilization), and also relates to an imaging apparatus or an optical apparatus that includes the image blur correction apparatus.
2. Description of the Related Art
Recent cameras can automatically perform essential image capturing processing (e.g., exposure determination and focus adjustment) to prevent users from failing in shooting operations even if the users are not skillful for camera operations. Further, imaging systems are configured to correct image blur that may be caused by a camera shake added to cameras. Thus, there is almost nothing about factors that may induce any errors in user's shooting operations.
An example system capable of correcting image blur caused by a camera shake is simply described below. The camera shake added to a camera in a shooting operation is vibration in the frequency range from 1 Hz to 10 Hz. To capture an image free from image blur even when such a camera shake occurs when a shutter release button is pressed, it is necessary to detect a camera shake caused by camera shake and move a lens to be used for image blur correction (hereinafter, referred to as “correction lens”) according to the detection value. Therefore, to capture an image free from image blur even when a camera shake occurs, it is necessary to accurately detect a camera shake (vibration) and correct a change of the optical axis caused by the camera shake.
Detection of the camera shake can be realized by a shake detection unit installed on a camera. In principle, the shake detection unit detects acceleration, angular acceleration, angular velocity, or angular displacement and performs processing for calculating an output for image blur correction. The camera system performs image blur correction based on the output of the shake detection unit.
As discussed in Japanese Patent Application Laid-Open No. 2-162320 or in Japanese Patent Application Laid-Open No. 11-167074, a conventional camera shake correction apparatus uses a pair of lenses of opposite powers and balances these lenses.
However, according to Japanese Patent Application Laid-Open No. 2-162320, a link mechanism (a beam structure) extends in an optical axis direction to hold the lenses of opposite powers in a balanced state. Therefore, the body size of the camera shake correction apparatus is relatively large. As the correction lenses are supported by beam members rotatably with respect to the beam members, camera shake correction may cause a positional deviation in the optical axis direction and may deteriorate the accuracy in the focus direction.
According to Japanese Patent Application Laid-Open No. 11-167074, the image blur correction apparatus is required for correcting each image blur of two axes and therefore the apparatus body cannot be downsized.